Background

Vitamin B3 is made up of niacin and niacinamide, and can be found in many foods, including yeast, meat, fish, milk, eggs, green vegetables, and cereal grains. Vitamin B3 is often found in combination with other B vitamins, including thiamine, riboflavin, pantothenic acid, pyridoxine, cyanocobalamin, and folic acid.

The U.S. Food and Drug Administration (FDA) has approved niacin for use in treating vitamin B3 deficiency (pellagra), which includes symptoms of skin inflammation, dementia, and diarrhea.

Human research has shown that niacin is effective and relatively safe for treating high cholesterol levels. Limited evidence shows that niacin may help with clogged arteries and heart disease. Side effects commonly related to higher doses of niacin are itching, flushing, and stomach upset. Niacin may also cause liver problems, increased blood sugar, and hormone changes.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (over 18 years old)

The dietary reference intake established by the Food and Nutrition Board for niacin ranges from 14-18 milligrams niacin daily by mouth for adults, with an upper intake level of 35 milligrams daily by mouth. Niacinamide and niacin are used in cosmetics, as well as hair and skin products. The concentration of niacinamide varies from a low of 0.0001% in night preparations to a high of 3% in body and hand creams, lotions, powders, and sprays. Niacin concentrations range from 0.01% in body and hand creams, lotions, powders, and sprays to 0.1% in paste masks (mud packs).

For age-related macular disease (eye disease), 500 milligrams of immediate-release niacin has been taken by mouth.

For preventing clogged arteries, 3,000-4,000 milligrams of niacin has been taken by mouth daily alone or in combination with other cholesterol therapy for 0.5-6.2 years.

For heart disease, 0.125-12 grams of niacin has been taken by mouth daily for up to five years.

For erectile dysfunction, 500-1,500 milligrams of niacin (Niaspan®) has been taken by mouth for 12 weeks.

For high cholesterol, 300-1,2000 milligrams of niacin has been taken by mouth daily for 6-44 weeks as wax-matrix, immediate-release (crystalline); 2 grams of niacin has been injected into the vein over 11 hours. The maximum recommended daily dose is 3 grams.

For high cholesterol (in combination with statins or bile acid sequestrants) 500-4,000 milligrams of extended-release or regular niacin has been taken by mouth daily for eight weeks to 6.2 years. Extended-or sustained-release niacin may be started at a dose of 500 milligrams daily and titrated up to 3 grams daily.

For high cholesterol levels in HIV-infected patients 500-2,000 milligrams of extended-release niacin (Niaspan®) has been taken by mouth daily for 44 weeks to two years.

For high blood phosphorous levels, a single 375 milligram dose of extended-release nicotinic acid has been taken by mouth.

For osteoarthritis, 3 grams of niacinamide has been taken by mouth daily for 12 weeks.

For pellagra, or niacin deficiency, 50-1,000 milligrams of niacin has been taken by mouth daily.

For skin conditions, 2-5% of niacinamide cream has been applied to the skin for up to 12 weeks.

For type 1 diabetes mellitus prevention, 200-3,000 milligrams of niacinamide has been taken by mouth daily for up to one year; 20-40 milligrams per kilogram of niacinamide has been taken daily by mouth for up to one year and lacked evidence of benefit.

For type 2 diabetes, 0.5 grams of nicotinamide has been taken by mouth three times daily for six months.

Children (under 18 years old)

There is no proven safe or effective dose for niacin in children.

For type 1 diabetes mellitus prevention, 200-3,000 milligrams of niacinamide has been taken by mouth daily for up to one year; 20-40 milligrams per kilogram has been taken by mouth daily for up to five years, and lacked evidence of benefit.

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

High cholesterol

Niacin is a well-accepted treatment for high cholesterol. Multiple studies show that niacin (not niacinamide) has benefits on levels of high-density cholesterol (HDL or "good cholesterol"), with better results than drugs such as "statins" like atorvastatin (Lipitor®). There are also benefits on levels of low-density cholesterol (LDL or "bad cholesterol"), although these effects are less dramatic. Adding niacin to a second drug such as a statin may increase the effects on low-density lipoproteins. The use of niacin for the treatment of high cholesterol associated with type 2 diabetes has been controversial because of the possibility of worsening blood sugar control. People should check with a physician and pharmacist before starting niacin.

A

Pellagra

Niacin (vitamin B3) and niacinamide are U.S. Food and Drug Administration (FDA)-approved for the treatment of pellagra, or niacin deficiency. Pellagra is a nutritional disease that occurs due to insufficient dietary amounts of vitamin B3 or the chemical it is made from (tryptophan). Symptoms of pellagra include skin disease, diarrhea, dementia, and depression.

B

Clogged arteries

Niacin decreases blood levels of cholesterol, which may reduce the risk of clogged or hardened arteries. However, niacin also can increase homocysteine levels, which may have the opposite effect. Overall, the research supports the use of niacin in combination with other drugs to reduce the risk of clogged arteries. More research is needed in this area before a firm conclusion can be drawn.

B

Heart disease

Niacin decreases levels of cholesterol, and other chemicals in the blood, which can reduce the risk of heart disease. However, niacin also increases homocysteine levels, which can increase this risk. Research has shown beneficial effects of niacin, especially in combination with other drugs, for preventing heart disease and fatal heart attacks. Further study is needed to draw conclusions.

C

Age-related macular disease (eye disease)

Early evidence suggests that niacin may have beneficial effects in age-related macular degeneration (AMD), a disease that often leads to vision loss. More well-designed studies are needed for conclusions to be reached.

C

Alzheimer's disease (mental decline)

Dementia can be caused by a severe lack of niacin in the body. Early evidence suggests that taking more niacin in the diet may slow the onset of Alzheimer's disease and mental decline. Further research is needed before a conclusion can be drawn.

C

Erectile dysfunction

Early research suggests that niacin has a beneficial effect on erectile dysfunction. However, further well-controlled studies are needed to draw conclusions.

C

Headaches

Early research shows that niacin may be beneficial in the treatment or prevention of headaches. More research is needed.

C

Hepatitis C

Early research suggests that niacin may decrease blood levels of hepatitis C, a virus that damages the liver. Notably, niacin has been also associated with liver damage. Further research is necessary for a conclusion to be made.

C

High blood phosphorous level

Early evidence shows that niacinamide had reduced high phosphate levels in the blood. However, more research is needed before a firm conclusion can be made.

C

Osteoarthritis (niacinamide)

Early research suggests that niacinamide may be useful in the treatment of osteoarthritis. Further research is needed before a conclusion can be made.

C

Skin conditions

Niacinamide has been used in skin care products, including moisturizers, anti-aging products, and treatments for rosacea, a skin condition involving facial redness and pimples. The benefits of niacinamide in skin care needs to be further studied before conclusions can be made.

C

Type 1 diabetes (slowing progression)

Non-human research shows that niacinamide delays the onset of insulin dependence in type 1 diabetes. However, human research assessing whether niacinamide slows progression of type 1 diabetes has yielded unclear results. Further study is needed for conclusions to be reached.

C

Type 2 diabetes

Limited research shows unclear effects of niacin on outcomes of type 2 diabetes. Human research has also shown that niacin increases blood sugar levels. People should seek medical advice before starting niacin. Further research is needed to draw conclusions.

D

Type 1 diabetes mellitus prevention (niacinamide)

In human research, niacinamide lacked an effect on the development of diabetes (type 1). Evidence is mixed and more study is needed in this area.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Interactions

Interactions with Drugs

Niacin may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).

Niacin may increase blood sugar levels. Caution is advised when using medications that may alter blood sugar. People taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

Niacin may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be altered in the blood, and may cause altered effects or potentially serious adverse reactions. People using any medications should check the package insert, and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.

Interactions with Herbs and Dietary Supplements

Niacin may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

Niacin may increase blood sugar levels. Caution is advised when using herbs or supplements that may alter blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

Niacin may cause low blood pressure. Caution is advised in people taking herbs or supplements that lower blood pressure.

Niacin may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements may be altered in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

Avoid in people with known allergy or sensitivity to niacin, niacinamide, or products containing one or both of these products.

Rarely, anaphylactic shock (severe allergic reaction) has been described after giving niacin by mouth or injecting it into the vein.

Side Effects and Warnings

Niacin is likely safe when taken by mouth daily in recommended amounts under the supervision of a qualified healthcare provider. Homocysteine levels should be monitored.

Niacin may increase blood sugar levels. Caution is advised in people with diabetes who are not monitored by a qualified healthcare provider and in those taking drugs, herbs, or supplements that affect blood sugar. Blood sugar levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.

Niacin may increase the risk of bleeding. Caution is advised in people with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.

Use cautiously in people with kidney disorders and gout.

Use cautiously in children.

Avoid in people with sensitivity to niacin, niacinamide, or products containing one or both of these products.

Avoid in people with liver dysfunction or disease, peptic ulcer disease, or arterial bleeding.

Pregnancy and Breastfeeding

There is a lack of research regarding the use of niacin during pregnancy and breastfeeding.

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